1. Field of the Invention
The present invention relates to a power window apparatus, and more particularly to a power window apparatus capable of opening windows for a predetermined time (e.g., five minutes) when an automobile falls into water.
2. Description of the Prior Art
Although conventional power window apparatus used in an automobile are designed to remain operational when the automobile falls into water, they often fail to operate as intended because the operation of their electrical system is made unstable by water, with the result that passages cannot escape from the automobile and their life may be risked. Accordingly, there is proposed a power window apparatus that retains its reliability and will function to open the windows for a predetermined time after the automobile falls into water.
Such a conventional power window apparatus will be described with reference to FIG. 4. As shown in FIG. 4, the power window apparatus includes a driving part 51, relays 52 and 53, transistors 55 and 60, a control part 58, a submergence detecting sensor 72, a window close switch (UP) 64, and a window open switch (Down) 65. The control part (hereinafter referred to as CPU) 58 comprises a microcomputer, ASIC (application-specific integrated circuit), and the like.
The driving part 51, which is a reversible motor for opening or closing open/close parts (hereinafter referred to as windows) not shown, rotates (Down) so as to open the windows when a current flows from the upper side to the lower side in a circuit shown in FIG. 3, and rotates (Up) so as to close the windows when a current flows from the lower side to the upper side.
The relays 52 and 53 respectively have switches 52a and 53a, and exciting coils 52b and 53b, and only when a control voltage is applied to only one of the exciting coils 52b and 53b, power from an automobile power terminal 54 is supplied to the driving part 51 via the switches 52a and 53a. 
The transistor 55 has: a base connected to an output pin P06 of CPU 58 via a resistor 56 and an inverter 57 in series; a collector grounded via the exciting coil 52b; and an emitter connected with an automobile power terminal 59.
A transistor 60 has: a base connected to an output pin P07 of CPU 58 via a resistor 61 and an inverter 62 in series; a collector connected with connected with one end of the exciting coil 53b; and an emitter connected with an automobile power terminal 63.
The CPU 58 has plural input-output pins; input pins (P71, P72, P73) are applied with voltages to serve as signals from the window close switch (UP) 64, the window open switch (Down) 65, and the submergence detecting sensor 72, and according to the signals, minute currents to serve as signals for turning the transistors 55 and 60 on or off are outputted from the output pins (P07, P06).
Both the window close switch (UP) 64 and the window close switch (Down) 65, only when operated, switch a connection destination of one end thereof from the ground to the automobile power terminal 66. Another end of the window close switch (UP) 64 is connected to the input pin P71 of the CPU 58 via an inverter 67 and a pullup power 68. Another end of the window open switch (Down) 65 is connected to the input pin P72 of the CPU 58 via an inverter 69 and a pullup power 70, and to another end of the exciting coil 53b. 
The submergence detecting sensor 72 comprises a pair of conductors disposed in opposed relation to each other and in proximity to each other, and when exposed to water, it is brought into conduction with a small resistance value so that one end thereof is grounded and the other end thereof is connected to an automobile power terminal 73 and the base of the transistor 74.
The transistor 74 has an emitter connected to the automobile power terminal 73 and a connector connected to the input pin P73 of the CPU 58.
With the above construction, when the window close switch (UP) 64 or the window open switch (Down) 65 is operated, a signal corresponding to the operated switch is inputted to the input pin P71 or P72 of the CPU 58. According to the inputted signal, the CPU 58 outputs a signal of minute current from the output pin P06 or P07 to the transistor 55 or 60 via the inverter 57 or 62. The transistor 55 or 60 is turned on or off by the outputted signal so that a voltage is applied to the exciting coil 52b or 53b. Accordingly, the switch 52a or 53a is switched so that the automobile power is supplied to the driving part 51, whereby the driving part 51 rotates forward or backward to open or close windows.
When the submergence detecting sensor 72 is exposed to water, the transistor 74 goes on because the base thereof goes into a ground voltage, and a voltage from the automobile power terminal 73 is inputted to the input pin P73 of the CPU 58. When the voltage is inputted to the input pin P73, the CPU 58 outputs minute currents of, e.g., +5 V from both the output pins P06 and P07, which are inputted to the transistors 55 and 60 via the comparators 57 and 62, with the result that both the transistors 55 and 60 are turned on. Since a voltage is applied to both the exciting coils 52b and 53b, both the switches 52a and 53a are switched and an equal voltage is applied to both input-output pins of the driving part 51, so that the driving part does not operate. Consequently, the windows do not operate, either.
At this time, when the window open switch (Down) 65 is operated, a connection destination of one end of the switch 65 is switched from the ground to the automobile power terminal 66. Then, since a series circuit from the automobile power terminal 63 having applied a voltage to the exciting circuit 53b is not grounded, a current flow is stopped, and since a higher voltage is developed at the cathode side of a diode 71 by the automobile power terminal 66, no voltage is applied to the exciting coil 53b. As a result, since a voltage is applied to only the exciting coil 52b and only the switch 52a is switched, the automobile power is applied to the driving part 51, which starts operation, so that the windows are opened.
By the above-described construction and operation, even if an automobile falls into water, the windows can be opened, so that occupants can escape from it.
However, this power window apparatus has the following problem. Parts and circuits except the CPU 58, upon submergence, undergo reduction in insulation resistance between terminals but operate for a predetermined time (e.g., five minutes), while the CPU 58, which performs control by slight currents, may cause malfunction or run away uncontrollably upon submergence. For example, a slight current of, e.g., +5 V, which is outputted from both the output pins P06 and P07 to turn on the transistors 55 and 60, leaks elsewhere at submergence, with the result that the slight current from the CPU 58 minus the leak current may yield to further result in failure of both the transistors 55 and 60 to be turned on, so that the windows may move in unexpected directions or may not be opened even if the window open switch (Down) 65 is operated.
The present invention has been made to solve the problem and provides a power window apparatus that, even if a CPU causes malfunction or becomes uncontrollable upon submergence, can prevent windows from performing unexpected operations and enables the windows to be opened without fail if desired.
To solve the problem, a power window apparatus of the present invention comprises: a driving part that has two current input-output ends, and drives automobile open/close parts open or close, depending on the direction of a driving current flowing via the current input-output ends; two relays which each have an exciting coil and a switching contact, wherein, when a current is fed to the exciting coil, the switching contact connects the current input-output end to a positive or negative pole of power; a submergence detecting sensor that drops in resistance value between both ends thereof when exposed to water; and a submergence-time escape switch that forcibly drives the open/close parts open upon submergence, wherein two transistors are provided which are connected in series with the exciting coils and feed a current to the exciting coils when turned on, and the base of each transistor is connected to a potential point through which a base current flows via the submergence detecting sensor.
By this construction, even if insulation resistance between terminals of discrete parts such as transistors drops because of submergence, currents can be fed to the exciting coils without fail and both switching contacts of the relays are switched, whereby voltages at the current input-output ends of the driving part become equal and the driving part is stopped, with the result that the Fiji operation of the open/close parts can be stopped without fail and the open/close parts can be opened by operating the submergence-time escape switch.
The power window apparatus of the present invention comprises: a driving part that has two current input-output ends, and drives automobile open/close parts open or close, depending on the direction of a driving current flowing via the current input-output ends; two relays which each have an exciting coil and a switching contact, wherein, when a current is fed to the exciting coil, the switching contact connects the current input-output end to a positive or negative pole of power; a submergence detecting sensor that drops in resistance value between both ends thereof when exposed to water; and a submergence-time escape switch that forcibly drives the open/close parts open upon submergence, wherein two transistors are provided which are connected in series with the exciting coils and feed a current to the exciting coils when turned on, and the base of each transistor is connected to a potential point through which a base current flows via a transistor the base of which is connected to a potential point through which a base current flows via the submergence detecting sensor.
By this construction, at submergence, the operation of the open/close parts can be stopped, and by operating the submergence-time escape switch, the open/close parts can be opened, and the submergence detecting sensor can detect submergence quickly and surely because, if a base current of one transistor flows, two transistors can be turned on.
Furthermore, the power window apparatus of the present invention is provided with a transistor that applies a voltage of automobile power to both ends of one of the exciting coils, wherein the transistor is turned on when the submergence detecting sensor is exposed to water and the submergence-time escape switch is operated.
By this construction, when the submergence-time escape switch is operated, since voltages of both ends of one of the exciting coils can be made equal, it can be further ensured that no current flows through the other of the exciting coils, and thereby the windows can be opened further surely when the submergence-time escape switch is operated.